Have you ever had a dream where you knew you were dreaming? This unusual state of consciousness is called lucid dreaming.
Lucid dreaming has long been a topic of interest in dream research. The term "lucid dreaming" was coined by Frederick van Eeden in 1911, who reported on lucid nightmares among other lucidity phenomena. In a lucid nightmare the dreamer is aware that he is dreaming and that the dream is a nightmare. The nightmare themes often involve demonic figures out to inflict terrible harm on the dreamer who struggles to wake up but can’t.
But the more common lucid dream is a typical dream where the dreamer is aware of the dream and has no strong desire to wake up and end the dream.
What is so fascinating about these dreams are the implications they hold for a theory of consciousness and identity.
Consider the fact that the dreamer quite clearly has awareness and self-consciousness. He can discriminate the real from the unreal so he is not insane. The ability to reason and to engage in logical thought is intact. Access to the dreamer’s autobiographical memories is intact. The ability to take on third person perspective is intact so the dreamer can consider, entertain and imagine what another character in the dream is thinking or feeling as well. Indeed whole interactions, dialogues between the dreamer and dream characters can take place just as in waking life.
The dream characters furthermore cannot be considered mere creations of the lucid dreamer, as they act as if they had full mental capacity and autonomy, and in nightmares they clearly act contrary to the wishes of the dreamer. In short, all of the constituents of Mind that we take for granted in waking life exist in the lucid dream state for both the dreamer and the dream characters.
But in addition to the normal elements of Mind present in the lucid state the lucid dreamer and other dream characters have added mental capacities. The lucid dreamer very often can make things happen in the dream that would be considered miraculous if they occurred in waking life. The lucid dreamer may be convinced he has supernatural mental powers in the lucid state.
The lucid dreamer furthermore can sometimes control the unfolding of the dream plot so he stands in relation to the dream characters just as a novelist does to his fictional characters—yet at the same time the dream characters confront the dreamer as real beings, even hyper-real beings as in the case of lucid nightmares. Here the dream characters can make things happen in the dream that are contrary to the will of the dream. Actions initiated by dream characters can cause everything from orgasms in the dreamer to near-death experiences in the dreamer.
There are testimonies on record, for example, of a dream character shooting a dreamer in the heart and the dreamer waking up with a heart attack. Is this a case of the dreamer confabulating a story line in order to explain the pain of a heart attack? We will never know. In all likelihood dream characters have "caused" death to dreamers as well, but we will never be able to document such an event.
Most interesting, of course, is the fact that the lucid dreamer is essentially a fully awake human person who cannot be said to be hallucinating (because he knows what is real and unreal); and yet who observes a fully realized visual world replete with settings, environments, characters, movements, actions, storyline, plot and "atomsphere" just as occurs in the waking world. Indeed this dream world and the characters in it are so real that they can intensely affect the dreamer’s physiologic reactions even unto death.
So how are we to understand lucid dreaming?
Philosophically I have seen no satisfactory account of the lucid dreamer in the literature though I have read many attempts. Specifically, no account I know of is willing to grant the lucid dreamer and the characters in the lucid dream full mental status, full person status—this despite the fact that all the characters in the lucid dream clearly evidence the mark of the mental.
What about physiologic accounts of the lucid dream? While the lucid dream does in fact emerge very often from the REM state (and that is why it is legit to call it a dream), it functions in some sort of hybrid REM-NREM transitional state or better REM-partial awakening state. Thus it is not strictly speaking a sleep state—even though it most often arises within a sleep state.
Lucid dreaming is not a waking state either however. Unlike relaxed wakefulness with eyes closed, lucid dreaming shows no evidence of alpha band activity on EEG and instead is characterized by sleep-related low frequency theta and delta activity. On the other hand, lucid dreaming consistently demonstrates heightened power at the 40-Hz frequency band, especially at frontal sites on the EEG.
We now have confirmation that lucid dreaming is indeed associated with reactivation of prefrontal networks during the lucid state. In a recent paper published in the journal SLEEP (Dresler M, Wehrle R, Spoormaker VI, Koch SP, Holsboer F, Steiger A, Obrig H, Sämann PG, Czisch M. 2012, Neural Correlates of Dream Lucidity Obtained from Contrasting Lucid versus Non-Lucid REM Sleep: A Combined EEG/fMRI Case Study. Sleep. Jul 1;35(7):1017-20), Dresler et al, managed to collect functional neuroimaging data on at least one out of four lucid dreamers they studied. While the dreamer was in the lucid state, bilateral precuneus, cuneus, parietal lobules, and prefrontal and occipito-temporal cortices displayed significantly greater activation as compared with the non-lucid REM state.
As the authors themselves pointed out, these areas of activation (e.g., the parietal and prefrontal lobes) overlap considerably with areas that are known to undergo de-activation during REM sleep. Thus, the neuroimaging data seem to confirm the idea that lucid dreaming is not a REM phenomenon even though it may begin in REM and some elements of REM (e.g., muscle paralysis) remain while in the lucid state.
While the fact that the prefrontal and parietal cortical networks are re-activated in lucid dreams, this fact only helps us explain access to logical thought and awareness while in the lucid state. The lucid dream’s most fascinating mysteries (especially as displayed in Van Eeden’s lucid nightmares) remain unexplained.